A-A-54520
Speed of thermometer response. The stem of the thermometer at room temperature shall be immersed in a liquid bath having a 32 degree (F) temperature. After the temperature dial registers 32 degrees (F), the thermometer shall be removed from the liquid bath and immediately immersed in a liquid bath having a 212 degree (F) temperature. The time for the dial to reach 180 degrees (F) from the 50 degree (F) reading shall be determined and recorded. Sampling for the testing shall be in accordance with MIL-STD-105 and an S-1 inspection level. The rejection number shall be two (2). Any thermometer whose time response exceeds 10 seconds shall be cause for rejection.
Stability of temperature reading. The thermometer stem shall be immersed in a liquid bath having a temperature within a range of 2 to 200 degrees (F). The thermometer dial reading of the bath shall be recorded after the dial setting has stabilized for at least two minutes. The thermometer shall be removed from the bath and then be subjected to vibration in accordance with the following:
The thermometer is mounted so that its dial is either normal or parallel to the direction of vibration.
The thermometer is subject4ed to two one hour vibration cycles (two hours total vibration time). Each cycle shall consist of the vibration frequency being progressively increased from 500 to 3000 cycles per minute during the first half hour and then progressively decreased back to 500 cycles per minute during the next half hour.
After the thermometer has completed its two cycles of vibration, it shall again be immersed in a liquid bath having the same temperature as that obtained for the initial reading. The thermometer dial reading of the water bath shall be recorded after the dial setting has stabilized for at least two minutes. Sampling for the testing shall be in accordance with MIL-STD-105 and an S-1 inspection level. The rejection number shall be two (2). Any thermometer whose temperature reading changes from its original reading by more than 2 degrees shall be cause for rejection.
Tightness of calibration nut. The thermometer calibration nut shall be subjected to a torque test to determine the externally applied force that is necessary to turn the calibration nut that controls the dial setting. The thermometer shall be held in a rigid position with the dial housing prevented from turning. The torque necessary to turn the calibration nut shall be determined by one of the following methods:
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